Nervous system part 3

transcript

Nervous System Part 3

• Presented By –

• Prof.Dr.R.R.Deshpande

(M.D in Ayurvdic

Medicine & M.D. in

Ayurvedic Physiology)

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Sharir Kriya -- Paper 1 –Part B –Point 4

• Prof.Dr.R.R.Deshpande (M.D in Ayurvdic

Medicine & M.D. in Ayurvedic Physiology)

• www.ayurvedicfriend.com

• Mobile – 922 68 10 630

• mailme.drrrdeshpande@rediffmail.com

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Memory ( Smruti in Ayurved)

• Memory is the ability to recall past

experienced or information

• Memory is also retention of learned

materials

Memory 2

Anatomical aspect of Memory

• The parts of the brain, associated with

memory are -----

• Association cortex of the frontal, parietal,

occipital, temporal lobes

• Limbic system (Hippocampus,

amygdaloid nucleus), Diencephalon.

Limbic system

Anatomical aspect of Memory

• There exists synapse for memory coding

• There are 2 separate pre synaptic

terminals (primary pre synaptic terminal &

facilitator terminal)

• When sensory terminal is stimulated

with facilitator terminal, signals remain

strong for few months or few years

Physiological aspect of memory

• Memory is stored in brain, by the alteration

of synaptic transmission.

• Through facilitation memory storage is

enhanced. This process is called as

memory sensitization

• Through in habituation, memory storage

is attenuated or decrease in strength.

This is negative memory

Memory 3

Types of memory

• Short term memory is the temporary

ability to recall a few pieces of information

• Long term memory last for days to years.

Types of memory

• In short term memory number of pre

synaptic terminals & size of terminals are

increased

• In long term memory neuronal circuit is

rein forced by constant activity, memory

is consolidated & encoded (at

Hippocampus & Papez circuit).

Types of memory

• Experimental studies of memory &

learning are carried out in the Sea snail,

called as Aplysia.

• Eric Kandel is the pioneer to use Aplysia

Chemical or molecular aspect of memory

• Memory Ingram is a process through

which memory is facilitated & stored in the

brain (by structural & biochemical

changes)

• This is memory trace.

Stages of Memory

Chemical or molecular aspect of memory

• Neurotransmitter serotonin plays a major

role in molecular basis of facilitation.

Calcium ions increase the release of

serotonin.

• Habituation is due to passive closure of

calcium channels of terminal membrane.

Consolidation of memory

• This is the process through which short

term memory is converted in to a long

term memory.

• Rehearsal of same information again &

again accelerates & potentiates this

transformation process.

• Long term potentiation (LTP) is related

with memory, neurotransmitter glutamate

stimulates release of nitric oxide (No) from

the post synaptic neurons

• NO is responsible for induction of LTP.

• Acetylcholine (Ach) also play an

important role in memory

• In Alzheimer’s disease, there is a depletion of

some part of brain region, where Ach is

synthesized

• Nucleic acids are also related with long term

memory

• DNA & RNA store information DNA persist for

lifetime of the cell

• If RNA formation is inhibited, long term

memory will not occur

• RNA synthesis depends up protein

synthesis

• So there is relation of Protein with

Memory

Clinical significance

• 1) Amnesia - this is loss of memory.

• Anterograde amnesia occurs due to

lesion in Hippocampus.

• There is failure to generate new long term

memories.

• In Retrograde amnesia, there is problem

to recall past remote memory

• It happens in temporal lobe syndrome.

Retrograde Amnesia

Clinical significance

• 2) Dementia –

• In addition to loss of memory, there is

progressive loss of intellect, emotional

control, social behavior & motivation

• This is common after the age of 65.

Causes of Amnesia & Dementia

• Most common is Alzheimer’s disease.

• Other causes are

• Hydrocephalus

• Parkinson’s

• Viral encephalitis

• HIV, Hypothyroidism

• Cushing’s syndrome • Alcoholic intoxication

• Poisoning by high dose of barbiturates,

• Heavy metals.

Alzheimer’s disease • This is progressive neurodegenerative disease.

• Death of neurons are in cerebral hemispheres

Hippocampus & pons.

• Due to deficiency of enzyme Choline acetyl

transferase, there is less synthesis of Ach.

• Due to degeneration of locus seruleus, synthesis

of nor epinephrine decreases.

Alzheimer's Brain

Alzheimer’s disease • Patient suffers from loss of recent memory, lack

of thinking & judgment. There are personality

changes.

• Further psychiatric features developed. Motor

functions are affected.

• Patient lives vegetative life without thinking

power. At moment no treatment is available.

• Physostigmine inhibits cholinesterase. This

gives moderate improvement

Learning

• Learning is a process, to acquire new

information.

• It is of 2 types –

• Non associative learning

• Associative learning.

Learning 2

Non associative learning

• Non associative learning is a response of

a person to only one type of stimulus

• It is based on Habituation & Sensitization

• Habituation is, getting used to something,

to which a person is constantly expose

• After some time a person is Habituated to

the stimulus & ignores it

• Sensitization is a process, by which the

body is made to become more sensitive to

a stimulus.

• This is amplification of response

• When same stimulus is combines with

another pleasant or unpleasant stimulus,

the person becomes more sensitive to

original stimulus.

• Eg. While driving on the road a person is

familiar to regular traffic sounds

• But if one day a person hears screaming,

he gets shocked or sensitized with this

stimulus.

Learning 4

Associative learning

• This is a complex process

• This is learning about relations between 2

or more stimuli at a time

• The example is conditioned reflexes

• This is the acquired reflex, which required

learning, memory & recall of previous

experiences.

Associative learning

• They are of 2 types ---

• Classical conditioned reflexes &

• Instrumental conditioned reflexes

• Very famous example of classical

conditioned reflex is demonstrated by the

classical Bell - Dog experiment, done by

Ivan Pavlov

Bell Dog Experiment

Learning 5

Instrumental conditioned reflexes

• To develop these type of reflexes the

animal is taught to perform some task in

order to obtained a reward or to avoid a

punishment

• Learning & memory are the

physiological basis of conditioned

reflexes.

Instrumental conditioned reflexes

• So, learning is the ability to acquire skills

through instructions or experience

• Capability for change with learning is

called as plasticity

• This is the ability to change behavior in

response to stimuli from the external &

internal environments.

Motivation

• Motivation is the psychological feature that

arouses an organism to act towards a desired

goal & elicits, controls, & sustains certain goal

directed behaviors

• It can be considered a driving force; a

psychological drive that compels an action

toward a desired goal

Self Motivation

Motivation

• For example, hunger is a motivation that

elicits a desire to eat

• Motivation has been shown to have roots

in physiological, behavioral, cognitive, &

social areas.

Motivation

• Motivation may be rooted in a basic

impulse to optimize well - being, minimize

physical pain & maximize pleasure

• It can also originate from specific physical

needs such as eating, sleeping/ resting, &

Theories & models

• Intrinsic & extrinsic motivation

• Motivation can be divided into 2 types

• Intrinsic (internal) motivation &

• Extrinsic (external) motivation

Intrinsic motivation

• Intrinsic motivation refers to motivation

that is driven by an interest or enjoyment

in the task itself

• Exists within the individual rather than

relying on external pressures or a desire

for reward

• Students who are intrinsically motivated

are more likely to engage in the task

willingly as well as work to improve their

skills

• Which will increase their capabilities

• Students are likely to be intrinsically motivated

if they:

• Attribute their educational results to factors

under their own control, also known as

autonomy

• Believe they have the skills which will allow them

to be effective agents in reaching their desired

goals without relying on luck

• Are interested in mastering a topic, not just in

achieving good grades.

• in

Motivation 2

Extrinsic motivation

• Extrinsic motivation refers to the

performance of an activity in order to

attain an outcome

• Extrinsic motivation comes from outside

of the individual

• Common extrinsic motivations are –

• Rewards (for example money or grades)

for showing the desired behavior &

• The threat of punishment following

misbehavior

• Competition is in an extrinsic motivator

because it encourages the performer to

win & to beat others, not simply to enjoy

the intrinsic rewards of the activity

• A cheering crowd & the desire to win a

trophy are also extrinsic incentives

Comparison of

intrinsic & extrinsic motivation

• Social psychological research has

indicated that extrinsic rewards can lead

to----

• Over justification and

• A subsequent reduction in intrinsic

motivation.

Self - control

• The self - control aspect of motivation is

increasingly considered to be a subset of

emotional intelligence

• It is suggested that although a person

may be classed as highly intelligent, they

may remain unmotivated to pursue

intellectual endeavors

Drives

• Basic drives could be sparked by

deficiencies such as hunger, which

motivates a person to seek food

• Whereas more subtle drives might be the

desire for praise & approval, which

motivates a person to behave in a manner

pleasing to others.

Incentive theory

• Studies show that if the person receives

the reward immediately, the effect is

greater, & decreases as delay lengthens

• Repetitive ‘Action – Reward’ combination can cause the action to become habit.

Incentive theory

• Motivation comes from 2 sources

• Oneself & from other people

• These 2 sources are called as ---

• Intrinsic motivation & extrinsic

motivation, respectively.

Escape - seeking model

• Escapism & seeking are major factors

influencing decision making.

• Escapism is a need to break away from a

daily life routine, turning on the television

& watching an adventure film

• whereas Seeking is -- desire to learn,

turning on the television to watch a

documentary.

Need theories

• Motivation, as defined by Pritchard &

Ashwood ------

• This is the process used to allocate

energy to maximize the satisfaction of

Herzberg's 2 - factor theory

• "Respect for me as a person" is -----

• One of the top motivating factors at any

stage of life

Herzberg distinguished between

• Motivators --- eg. challenging work,

recognition, responsibility which give

positive satisfaction and

• Hygiene factors -- eg. status, job security,

salary and fringe benefits that do not

motivate if present, but, if absent, result in

demotivation.

Motivator - Hygiene Theory

• The name Hygiene factors is used

because, like hygiene, the presence will

not make you healthier, but absence can

cause health deterioration

• The theory is sometimes called the

"Motivator - Hygiene Theory" and/or "The

Dual Structure Theory. "

Physiology of sleep

• Limbic System

• Certain components of the cerebral

hemisphere & diencephalon constitute the

limbic (Limbus = Border) system

• Research work shows -- its association

with a control of visceral functions as a

primary area for emotional expression

& outlets.

Sleep 1

Limbic System(IMP regions)

• 1) Cortex (Limbic Lobe) - Largest components

are Para - hippocampal & Cingulate Gyri (both

gyri of cerebral hemispheres) & Hippocampus,

which extends into the floor of the lateral

ventricle

• 2) Dentate Gyrus

• 3) Amygdaloid body (Amygdala) 4) Septal

Nuclei

Limbic System

• 5) Mammillary bodies of the

hypothalamus

• 6) Anterior nucleus of the hypothalamus

• 7) Olfactory bulbs

• 8) Bundles of interconnecting myelinated

axons.

Limbic System

• The Limbic System is a wishbone

shaped group of structures that encircles

the brain stem & functions in the

Emotional aspects of behavior related to

survival

• The Hippocampus, together with portions

of the cerebrum also functions in Memory.

Limbic System

• Memory impairment results from lesions in

the limbic system

• Experiments on the limbic system of the

monkeys & other animals indicate that the

Amygdaloid Nucleus assumes a major

role in controlling the overall pattern of

behavior.

Limbic System

• Limbic System is associated with Pleasure & Pain

• Stimulation of the perifornical nuclei of the

hypothalamus results in a behavioral pattern called

• The animal assumes a defensive posture - extending its

claws, raising its tail, hissing, spitting, growling &

opening its eyes wide. Stimulating other areas of the

limbic system results in an opposite behavioral pattern -

docility, tameness & affection.

Limbic System

• Limbic system assumes a primary function

in emotions such as pain, pleasure, anger,

rage, fear, sorrow, sexual feelings, docility

& affection

• Hence called as Visceral or Emotional

• Definition –

• A state of consciousness, that differs from

alert wakefulness, by a loss of critical

reactivity, to events in the environment &

accompanied by a profound alteration in

the function of the brain.

• Rhythm - One sleep period in 24 hours

• It also depends on habit

• Commonly, sleep occurs during the

period of rest i.e. - at night

• In night workers, day sleeping is the habit.

• Requirement - Varies inversely with age

• New born baby - 16 - 20 Hours

• Children - 12 - 14 Hours

• Adults - 7 - 9 Hours

• Old age - 5 Hours

• Curve –

• 1) In adults - Max. depth at the end of 1st

• 2) In children - 2 max. periods -

• a) Between 1st & 2nd hour.

• b) Between 8th & 9th hour.

• (No dreams during deep sleep.)

Physiological responses during sleep

• 1) C. V. S. - Pulse ↓, B. P. ↓ • 2) RS - Rate ↓ • 3) B. M. R. - ↓

• 4) Secretions - Salivary & lacrimal - ↓ • Gastric - ↑ or unaltered • Sweat - ↑

Physiological responses during sleep

• 5) Muscles - Relaxed.

• 6) Eyes -- Eye - balls - roll up & out

• (Due to flaccid external ocular muscles),

• Eye lids - come closer (due to drooping of the

upper lids),

• Pupils – contracted

• 7) CNS - EEG = Appearance of δ waves, • Deep Reflexes - ↓, Babinski - Extensor

Different stages during sleep

• 1) Light sleep = Rapid Eye Movement

Sleep (REM Sleep) = Rhomben - cephalic

sleep - During this stage, high incidence of

penile erection & grinding of teeth

(Bruxism)

• 2) Non Rapid Eye Movement Sleep

(NREM Sleep) = Slow Wave Sleep.

Sleep Types

Sleep Cycle

Sleep stages Graph

Causes of sleep

• 1) Howell's Theory of Cerebral Ischaemia

• The drowsiness after food is due to splanchnic

vasodilatation, fall of B. P. & consequent

cerebral ischaemia.

• 2) Biochemical theories

• a) Acetylcholine - Acetylcholine is closely related

to functional integrity of the nervous system. It is

claimed that sleep is due to the accumulation of

Acetylcholine in the cerebral cortex.

Causes of sleep

• b) Hypnotoxin - Some scientists claim that

hypnotoxin, which is liberated from the brain

tissue, produces sleep.

• c) Lactic Acid - During fatigue, lactic acid

accumulates in the tissues. Lactic acid

depresses the activities of the cerebral cortex.

(But what is real ? - In fatigue, there is often

sleeplessness & oxidation of lactic acid occurs

which supplies energy to the brain, which

disapprove this theory.)

Causes of sleep

• 3) Kleitman's Theory

• More acceptable than others. Due to reduction

of muscle tone & discharge of less afferent

impulses, cerebral cortex remain inactive.

• Fatigue of the muscle with consequent reduction

of transmission of afferent impulses to the

cerebral cortex & thereby keeping it inactive

seems to be a plausible factor in the production

of sleep.

Sleep position & Personality

Pathology

• Insomnia –

• Abnormal wakefulness or inability to sleep

Insomnia

Effects of insomnia

• (Symptoms observed, when subjects keep

awake for 60 - 114 hours) –

• Equilibrium – disturbed

• Neuromuscular fatigue

• mental concentration difficult &

inaccurate

• Threshold for pain – lowered

• Babinski - Extensor

Complications of Insomnia

Effect of Sleep deprivation

Insomnia 2

Dreams

• Dreams are successions of images, ideas,

emotions, and sensations that occur

involuntarily in the mind during certain

stages of sleep.

• The content & purpose of dreams are not

definitively understood

• Dreams have been a topic of scientific

speculation, philosophical & religious interest.

Dreams

• The scientific study of dreams is called

Oneirology

• Scientists believe that, in addition to

humans, certain birds & the majority of

mammals also dream.

Dreams

• Dreams mainly occur in the rapid - eye

movement (REM) stage of sleep - when brain

activity is high & resembles that of being awake

• REM sleep is revealed by continuous

movements of the eyes during sleep

• Dreams may occur during other stages of sleep,

however, these dreams are not memorable

Dreams

• Dreams can last for a few seconds, or as long as

twenty minutes

• People are more likely to remember the dream

if they are awakened during the REM phase

• The average person has about 3 to 5 dreams

per night, but some may have up to 7 dreams in

1 night

Dreams

• The dreams tend to last longer as the

night progresses

• During a full 8 - hour night sleep, 2

hours of it is spent dreaming

Dreams

• In modern times, dreams have been seen as a

connection to the unconscious

• They range from normal & ordinary to bizarre

• Dreams can have varying natures, such as

frightening, exciting, magical, melancholic,

adventurous, or sexual

• Dreams can at times make a creative thought

occur to the person or give a sense of

inspiration.

Dreams

• Dream interpretations date back to 5000 - 4000

• The Austrian neurologist Sigmund Freud, who

developed the discipline of psychoanalysis,

wrote extensively about dream theories &

interpretations.

• He explained dreams as manifestations of our

deepest desires & anxieties, often relating to

repressed childhood memories or obsessions.

Cultural meaning

• The Mesopotamians believed that the soul, or

some part of it, moves out from the body of the

sleeping person & actually visits the places &

persons the dreamer sees in his sleep.

• Ancient Egyptians believed that dreams were

like oracles, bringing messages from the gods.

• They thought that the best way to receive divine

revelation was through dreaming & thus they

would induce dreams.

Cultural meaning

• The Greeks shared their beliefs with the

Egyptians on how to interpret good &

bad dreams, & the idea of incubating

dreams.

• Greek philosopher, Aristotle (384 - 322

BC) believed dreams caused physiological

activity. He thought dreams could analyze

illness and predict diseases.

Dynamic psychiatry

• Freudian view of dreams

• In the late 19th century, psychotherapist

Sigmund Freud developed a theory that

the content of dreams is driven by

unconscious wish fulfillment.

• Freud called dreams the "royal road to the

unconscious".

Dynamic psychiatry

• Freudian view of dreams

• He theorized that the content of dreams

reflects the dreamer's unconscious mind &

specifically that dream content is shaped

by unconscious wish fulfillment.

• He argued that important unconscious

desires often relate to early childhood

memories & experiences

The neurobiology of dreaming

• Accumulated observation has shown that

dreams are strongly associated with rapid

eye movement sleep.

• During REM sleep, the release of the

neurotransmitters norepinephrine,

serotonin & histamine is completely

suppressed

Dreams in animals

• REM sleep & the ability to dream seem to

be embedded in the biology of many

organisms that live on Earth.

• All mammals experience REM.

Dreams in animals

• The range of REM can be seen across

species:

• Dolphins experience minimum REM,

• While humans remain in the middle &

• The opossum & the armadillo are among

the most prolific dreamers.

Other hypotheses on dreaming

• There are many other hypotheses about

the function of dreams, including:--

• Dreams allow the repressed parts of the

mind to be satisfied through fantasy

while keeping the conscious mind from

thoughts that would suddenly cause one to

awaken from shock.

Other hypotheses on dreaming

• Freud suggested that bad dreams let the brain

learn to gain control over emotions resulting

from distressing experiences.

• Jung suggested that dreams may compensate

for one - sided attitudes held in waking

consciousness.

• Ferenczi proposed that the dream, when told,

may communicate something that is not being

said outright

Relationship with medical conditions

• There is evidence that certain medical

conditions (normally only neurological

conditions) can impact dreams

• For instance, some people with

synesthesia have never reported entirely

black & white dreaming, & often have a

difficult time imagining the idea of

dreaming in only black & white

Relationship with medical conditions

• Therapy for recurring nightmares

• Often associated with posttraumatic stress

disorder –

• Can include imagining alternative

scenarios that could begin at each step of

the dream.

Electro - Encephalography - EEG

• This is the recording of electrical activity

along the scalp.

• EEG measures voltage fluctuations,

resulting from ionic current, flows within

the neurons of brain.

EEG Electrode placement

• EEG = recording of brains spontaneous

electrical activity for 20 - 40 min recorded with

multiple electrodes, placed on scalp.

• This is the main diagnostic test for epilepsy.

• It is also helpful in the diagnosis of coma,

encephalopathies & brain death.

• It is also used in the studies of sleep &

sleep disorders (recording is done for 1 full

night)

• EEG was first line method to diagnose

tumors, stroke & other focal brain

disorders.

• This use is decreased with the advent

of MRI & CT

Source of EEG activity

• Electrical charging of brain is maintained by

neurons.

• Neurons are constantly exchanging ions with

the extracellular surrounding.

• When wave of ions reaches the electrodes on

scalp, they can push or pull electrons on the

metal of electrodes.

• The difference in push or pull voltages

between any 2 electrodes can be

measured by a voltmeter.

• Recording these voltages for particular

time gives EEG.

• Scalp EEG activity shows oscillations at

a variety of frequencies.

• These oscillations have characteristic

frequency ranges.

• These ranges are associated with different

states of brain functioning (like waking

state & various sleep stages.)

Clinical use of EEG

• 1) To distinguish epileptic seizures from

other types of convulsions like

psychogenic nonepileptic fits, cyncope or

fainting.

• 2) To differentiate organic encephalopathy

or delirium from psychiatric syndromes like

catatonia.

• 3) This is an adjuvent test for brain death.

Clinical use of EEG

• 4) To make prognosis of comatose

patients.

• 5) To decide whether to reduce

antiepileptic drugs.

Clinical use

• Sometimes a routine EEG is not sufficient & EEG is

constantly recorded during actual epileptic fit.

• This is done to differentiate-

• 1) Between epileptic fits from non epileptic convulsions.

• 2) To identify the character of seizure for giving

different types of treatments.

• 3) To localize the region from the brain where a seizure

originates (for work up of possible seizure surgery)

EEG can be used

to monitor certain procedures

• 1) To monitor the depth of anesthesia.

• 2) This is indirect indicator of cerebral

perfusion in carotid end arterictomy

• First human EEG recording was obtained

by Han’s Burger in 1924.

EEG can be used

to monitor certain procedures

• EEG does not involve exposure to high

intensity magnetic field as in MRI

• It also does not involve exposure to radio

- ligends unlike positron emission

tomography.

EEG - limitations & disadvantages

• 1) Lower resolution (MRI) can directly

display areas of brain which are active,

while EEG requires intense interpretation

to decide which areas are activated by a

particular response

• 2) EEG determines neural activity, which

occurs below cortex of brain very poorly

EEG - limitations & disadvantages

• 3) Unlike PET & MRS, EEG can not

identify specific locations at which various

neurotransmitters drugs can be found

• 4) Takes a long time to connect a patient

to EEG (precise placements of many

electrodes around head - Less time for

MRI etc.)

Method for EEG

• Recording is obtained by placing

electrodes on scalp with a conductive gel

or paste

• (after preparing scalp area by light

abrasion to reduce impedance due to

dead skin cells)

Method for EEG

• Electrodes are attached to individual wire,

19 electrodes with earthlings are used

• In neonates they are less in number

• Each electrode is connected to one input

of differential amplifier

• Digital EEG signal is stored electronically

& can be filtered for display.

Method of EEG

• Adult human EEG signal is about 10 μv - 100 μv in amplitude

• EEG is read by neurologist

• EEG is described in terms of rhythmic

activity & transients

Wave patterns in EEG

• 1) Delta waves (δ)

• Frequency range up to 4 Hz. Highest in

amplitude & shortest wave. It is seen in adults, in

slow wave sleep, also seen in babies.

• Pathologically, it may be seen locally with sub

cortical lesions & in general distribution with

metabolic encephalopathy, hydrocephalus

• 2) Theta waves (θ)

• Range from 4 - 7 Hz.

• Seen normally in young children or in

drowsiness.

• Also seen during meditation.

• Pathologically same like δ waves.

• 3) Alpha waves (α) • Frequency 8 - 12 Hz. Seen in posterior

region of head on both the sides

• It emerges with closing of eyes & with

relaxation & attenuates with eye opening

or mental exertion.

• 4) Beta waves ( )

• Range from 12 - 30 Hz.

• Beta activity is closely linked to motor

behavior & alternated during active

movements

• It may be absent or reduced in areas of

cortical damage

• 5) Gamma waves ( )

• Range from 30 - 100 Hz

• They are seen in certain cognitive or

motor functions

• EEG varies with age & also state of mind

EEG Waves

EEG during sleep

• 1) Stage I seep - increase in θ (Theta) frequency.

• 2) Stage II sleep - characterized by spindles.

Range - 12 - 14 Hz.

• 3) Stage III & IV sleep - called as (slow wave

sleep). Presence of δ (delta) frequencies (non

rapid eye movements)

• Stage III & IV sleep = NREM

• The EEG in REM sleep is similar to awake EEG.

Physiology of Temperature Regulation

• Birds & mammals (Man) are warm

blooded animals or homeothermic animals

• Body temperature is maintained at a

constant level, irrespective of the

environmental temperature

• Amphibians & reptiles are poikilo thermic

or cold blooded animals

• Temperature can be measured in the

mouth, axilla, rectum

• Rectal temperature is higher than oral

• oral is higher than axillary temperature

• Normal oral temperature varies between

96.4 to 99.10F

• core temperature of the body is 100F in

human being.

• Physiological variation of body

temperature can occur as per ----

• Age, sex,

• Diurnal variation,

• After meals, exercise,

• Sleep, emotion,

• Menstrual cycle.

• Hyperthermia or fever is abnormal

increase in the body temperature

• Fever is mostly caused by bacteria &

there toxins & viruses

• Decrease body temperature is called as

hypothermia.

• Normal body temperature is maintained by

the hypothalamus, with the help of ---

• Heat loss centre (situated in pre optic

nucleus of anterior hypothalamus) &

• Heat gain centre. (situated in posterior

hypothalamic nucleus)

• The hypothalamic thermostat is in the pre

optic area.

• Body temperature is depend on the

metabolic rate of the body

• Metabolic rate is affected by ---

• Exercise, the nervous system, hormones,

ingestion of food, age, sex, climate, sleep

& malnutrition.

• Heat is retained in the body through ---

• Vasoconstriction, sympathetic stimulation,

skeletal muscle contraction & thyroid

hormone production

• Heat loss occur through ----

• Radiation, evaporation, conduction &

convection

Temperature Regulation

• Radiation is the transfer of heat from a

warmer object to a cooler object, without

physical contact

• Evaporation is the conversion of liquid to

a vapor

• Conduction is the transfer of body heat to

a substance or object in contact with the

• Convection is transfer of body heat by a

liquid or gas, between areas of different

temperatures

Heat Loss

Heat Loss Mechanism

Mechanism of temperature regulation

• 1) When body temperature increases,

temperature regulation occur by 2

mechanisms –

• a) promotion of heat loss

• b) prevention of heat production.

• Promotion of heat loss occur, by

increasing the secretion of sweat

(Diaphoretic ,internal medicine)

Mechanism of temperature regulation

• By inhibiting sympathetic centers in

posterior hypothalamus (it causes

coetaneous vasodilatation, causing

excessive sweating)

• Heat loss centre prevents heat production

by inhibiting, shivering & metabolic

reactions.

• 2) What happens when body

temperature decreases? –

• Temperature is brought back to normal by

preventing heat loss & promotion of heat

production.

Heat production is promoted by

following ways

• 1) Shivering –

• Heat gain centre stimulates the primary

motor centre for shivering, when

enormous heat is produced, because of

severe muscular activities

following ways

• 2) Metabolic reactions are increased -

sympathetic centers are activated by heat

gain centre

• They stimulate secretion of adrenaline &

nor adrenaline

• Adrenaline accelerates cellular metabolic

activities.

following ways

• Also hypothalamus secretes thyrotropin

releasing hormone, which releases TSH

• Thyroxin accelerates the metabolic

activities.

following ways

• 3) Chemical thermo genesis –

• Heat is produced by metabolic activities,

induced by hormones

Practical importance

• If temperature regulation is disturbed, 2

problems can arise –

• Hyperthermia or fever

• Hypothermia

Fever - 3 types

• Mild Fever --- ------------- 98.5 to 100.4 F

• Low grade fever ----------- 100.4 to 102.2 F

• Moderate grade fever ----- 102.2 to 104 F

• High grade fever ------------- 104 to 107.6 F

Causes of fever

• Infection

• Hyperthyroidism

• Brain lesion

Clinical features of fever

• Warm body ,Headache, sweating,

• Shivering,

• Muscle pain,

• Dehydration,

• Weakness.

• In high grade fever there is convulsions,

confusion, irritability & hallucinations.

Heat Stroke

Treatment of Hyperthermia

Hypothermia - 3 types

• Mild hypothermia ---------- 95 to 91.4 F

• Moderate hypothermia ---91. 4 to 87.8 F

• Severe hypothermia -------below 87.8 F

Causes or hypothermia

• Exposure to cold temperature

• Immersion in cold water

• Hypothyroidism

• Drug abuse

• Lesion in hypothalamus

• Haemorrhage in pons.

Clinical features of hypothermia

• In mild hypothermia ---

• Uncontrolled intense shivering,

• Pain

• Discomfort.

Hypothermia

Hypothermia Symptoms

• In moderate hypothermia --

• Shivering stops but muscles become stiff

• Mental confusion,

• Shallow respiration,

• Weak pulse,

• Low BP.

• In sever hypothermia ---

• Weakness & exhaustion

• Skin becomes bluish gray

• Eyes are dilated

• Person loses consciousness

Prof.Dr.R.R.Deshpande

• Sharing of Knowledge

• FOR

• Propagating Ayurved

7/2/2016 173 Prof.Dr.R.R.Deshpande

Nervous system part 3

Education